When asked where the wettest place on Earth is, a typical smug response might be the Mariana Trench.
With more than 10,000 metres of water above it, the deepest spot in our oceans is undoubtedly wet. But if you’re discussing the wettest place on land the answer is a little trickier.
The current record holder, as recognised by the Guinness Book of World Records, is the cluster of hamlets known as Mawsynram in India. Moisture swept from the Bay of Bengal, condenses over this 1,491m plateau, in the Khasi Hills that overlook the plains of Bangladesh.
The result is an astonishing average annual rainfall of 11,871 mm (467.35”). Even the world’s biggest statue, Rio de Janeiro’s 30m tall Christ the Redeemer, would be up to his knees in that volume of water.
Unsurprisingly the area is overwhelmingly lush and green, rich with waterfalls and fascinating caves carved in the limestone by the falling water.
Ten miles to the East lies the town of Cherrapunji. It’s known locally by its traditional name Sohra and is the second wettest place on earth.
The abode of the clouds
Its average record falls shy of Mawsynram’s by 100mm but it holds plenty of other titles. It is still the location of the wettest month and year ever recorded.
In July 1861, the rainfall measured 9,300 mm (366”). Since the previous August, Cherrapunji measured a record-breaking annual total of 26,470 mm (1042”).
These extraordinary wet patches are both found in the state of Meghalaya, which translates as the abode of the clouds. People living here travel under umbrella shields called “knups” woven from reeds.
These shelter their whole bodies from the persistent downpours so they can still go about their daily business, much of which is repairing rain damage to roads and buildings or trading for food. Farming in the area is made impossible by the heavy rain so produce from drier climes is sold in tarpaulin-draped markets.
One of the other significant problems is maintaining bridges through the surrounding rainforest, where traditional building materials soon rot away.
When the bamboo eventually disintegrates, a living bridge remains
The ingenious solution is to knot and tie the roots of the trees themselves into structures that can weather the damp conditions.
Indian rubber trees (Ficus elastica) have strong, flexible secondary roots that grow out from the trees’ trunks. These roots are encouraged across streams and rivers by local people using hollowed out betel nut tree tunks as guides. They are then woven across bamboo structures.
Once the roots reach the soil on the other side they grow stronger. When the bamboo eventually disintegrates, a living bridge remains.
It takes around a decade to develop a living bridge but they can last hundreds of years, the oldest known in the area are said to be over 500 years old.
While the settlements of the Khasi hills have historical rainfall records locked down, there has recently been speculation that the world’s wettest place could be elsewhere.
Both the main challengers are found in Colombia but neither can technically be compared to the Indian champions.
Lloro is a town in north-western Colombia. On a farm nearby average annual rainfall between 1952 and 1954 was recorded at 13,473mm. That’s a good deal higher than Mawsynram’s average but it was made using outdated gauges so it can’t lay claim to any official title.
According to weather historian Christopher C Burt, across the Andes lies another town that’s also in a bit of a puddle when it comes to extreme rainfall records.
“In reality, the wettest location in the world is Puerto Lopez, Colombia with an average annual precipitation of 12,892 mm (507.56”),” he says.
There is a constant moist tropical onshore flow
But Burt explains that despite over 50 years of recording at this location, there are data missing for several months in the middle. This means Puerto Lopez’s rainfall record is interrupted and can’t be compared with other locations around the world that have 30 continuous years of data.
“However, given how long the Lopez [period of record] is and how many years of complete data there are, then I can say with confidence that Puerto Lopez normally receives more precipitation in an average year than Mawsynram does,” says Burt.
This Colombian rain town is wet year-round thanks to its position near the base of the northern Andes that run across the west of the country.
There’s an obvious difference between average rainfall and the probability of getting wet
“There is a constant moist tropical onshore flow from the Pacific Ocean here… the mountains block that flow and almost perpetual rainfall results over Puerto Lopez. I believe it averages over 320 days of rain a year. The rainfall is more or less evenly distributed around the year,” explains Burt.
Where rainfall is distributed is definitely the dividing factor when it comes to recognising the wettest place on Earth.
There’s an obvious difference of opinion between average rainfall measurements and the probability of actually getting wet. For example, while you might get soaked in Mawsynram, you’re even more likely to leave Puerto Lopez with squelchy shoes.
Until recently the wettest recorded 48 hour period occurred during a tropical cyclone on Reunion Island in the Indian Ocean. This raised the question: can a single extreme weather event see the Reunion Islands reign supreme?
This idea was swept aside in spring 2014 when a panel from the World Meteorological Organisation concluded that Cherrapunji now holds the two-day rain record with a staggering 2,493 mm (98.15”) measured on 15 to 16 June 1995.
This brings us back to the state of Meghalaya. The root of this state’s rainy reputation is the legendary monsoon. This is the seasonal prevailing wind that brings extreme rainfall to parts of South and South East Asia every year.
Thanks to the monsoon, as much as 90% of Mawsynram’s record-breaking annual rainfall can actually fall in just six months, from May to October. July is the wettest month of all here with the world’s highest monthly average rainfall of over 3500mm (120”).
But in the dry winter months from December to February, very little rain falls.
When local people struggle for drinking water, the title of the wettest place on Earth becomes its biggest paradox.